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Perl driver for dynamixel servo motors. This is the repo for Device::Dynamixel at CPAN

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README.pod

OVERVIEW

This is a simple driver for control of Robotis Dynamixel servo motors. This repository stores the history for the Device::Dynamixel module on CPAN. Install the module via CPAN. CPAN page at http://search.cpan.org/~dkogan/Device-Dynamixel/lib/Device/Dynamixel.pm

NAME

Device::Dynamixel - Simple control of Robotis Dynamixel servo motors

SYNOPSIS

 use Device::Dynamixel;

 open my $pipe, '+<', '/dev/ttyUSB0' or die "Couldn't open pipe for reading and writing";
 my $motorbus = Device::Dynamixel->new($pipe);

 # set motion speed of ALL motors to 200
 $motorbus->writeMotor($Device::Dynamixel::BROADCAST_ID,
                       $Device::Dynamixel::addresses{Moving_Speed_L}, [200, 0]);

 # move motor 5 to 10 degrees off-center
 $motorbus->moveMotorTo_deg(5, 10);

 # read the position of motor 5
 my $status = $motorbus->readMotor(5,
                                   $Device::Dynamixel::addresses{Present_Position_L}, 2);
 my @params = @{$status->{params}};
 my $position = $params[1]*255 + $params[0];

DESCRIPTION

This is a simple module to communicate with Robotis Dynamixel servo motors. The Dynamixel AX-12 motors have been tested to work with this module, but the others should work also.

A daisy-chained series string of motors is connected to the host via a simple serial connection. Each motor in the series has an 8-bit ID. This ID is present in every command to address specific motors. One Device::Dynamixel object should be created for a single string of motors connected to one motor port.

These motors communicate using a particular protocol, which is implemented by this module. Commands are sent to the motor. A status reply is sent back after each command. This module handles construction and parsing of Dynamixel packets, as well as the sending and receiving data when needed.

EXPORTED VARIABLES

To communicate with all motor at once, send commands to the broadcast ID:

 $Device::Dynamixel::BROADCAST_ID

All the motor control addresses described in the Dynamixel docs are defined in this module, available as

 $Device::Dynamixel::addresses{$value}

Defined values are:

 ModelNumber_L
 ModelNumber_H
 Version_of_Firmware
 ID
 Baud_Rate
 Return_Delay_Time
 CW_Angle_Limit_L
 CW_Angle_Limit_H
 CCW_Angle_Limit_L
 CCW_Angle_Limit_H
 Highest_Limit_Temperature
 Lowest_Limit_Voltage
 Highest_Limit_Voltage
 Max_Torque_L
 Max_Torque_H
 Status_Return_Level
 Alarm_LED
 Alarm_Shutdown
 Down_Calibration_L
 Down_Calibration_H
 Up_Calibration_L
 Up_Calibration_H
 Torque_Enable
 LED
 CW_Compliance_Margin
 CCW_Compliance_Margin
 CW_Compliance_Slope
 CCW_Compliance_Slope
 Goal_Position_L
 Goal_Position_H
 Moving_Speed_L
 Moving_Speed_H
 Torque_Limit_L
 Torque_Limit_H
 Present_Position_L
 Present_Position_H
 Present_Speed_L
 Present_Speed_H
 Present_Load_L
 Present_Load_H
 Present_Voltage
 Present_Temperature
 Registered_Instruction
 Reserved
 Moving
 Lock
 Punch_L
 Punch_H

To change the baud rate of the motor, the Baud_Rate address must be written with a value

 $Device::Dynamixel::baudrateValues{$baud}

The available baud rates are

 1000000
 500000
 400000
 250000
 200000
 115200
 57600
 19200
 9600

Note that the baud rate generally is cached from the last time the motor was used, defaulting to 1Mbaud at the start

STATUS RETURN

Most of the functions return a status hash that describes the status of the motors and/or returns queried data. This hash is defined as

 { from   => $motorID,
   error  => $error,
   params => \@parameters }

If no valid reply was received, undef is returned. Look at the Dynamixel hardware documentation for the exact meaning of each hash element.

CONSTRUCTOR

new( PIPE )

Creates a new object to talk to a Dynamixel motor. The file handle has to be opened and set-up prior to constructing the object.

METHODS

pingMotor( motorID )

Sends a ping. Status reply is returned

writeMotor( motorID, startingAddress, data )

Sends a command to the motor. Status reply is returned.

readMotor( motorID, startingAddress, howManyBytes )

Reads data from the motor. Status reply is returned.

writeMotor_queue( motorID, startingAddress, data )

Queues a particular command to the motor and returns the received reply. Does not actually execute the command until triggered with triggerMotorQueue( )

triggerMotorQueue( motorID )

Sends a trigger for the queued commands. Status reply is returned.

resetMotor( motorID )

Sends a motor reset. Status reply is returned.

syncWriteMotor( motorID, startingAddress, data )

Sends a synced-write command to the motor. Status reply is returned.

moveMotorTo_deg( motorID, position_degrees )

Convenience function that uses the lower-level routines to move a motor to a particular position

BUGS

An issue is the baud rate of the serial communication. The motors default to 1M baud. This is unsupported by the stock POSIX module in perl5, so the serial port must be configured externally, prior to using to this module.

REPOSITORY

https://github.com/dkogan/dynamixel

AUTHOR

Dima Kogan, <dima@secretsauce.net>

LICENSE AND COPYRIGHT

Copyright 2011 Dima Kogan.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.

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